A par rate is the standard interest rate that corresponds to the yield on a particular Treasury security. The par rate is used as a benchmark for pricing other debt instruments such as mortgage rates. For example if the par rate for a 10-year Treasury security is 2.5% then a lender may price a 30-year mortgage at 3.5% (1.0% above par).
What is the par rate on a mortgage?
The par rate is the interest rate at which the lender is willing to loan money to the borrower.